Embodiments of the present disclose relate to protecting structures from dynamic loading, and more specifically, to composite sleeve rod axial dampeners for buildings and structures.
When a structural member is excited by a horizontal external force, shear or similar horizontal movement may occur. Shear, especially in high building structures or towers may have serious impact on the conditions of the structure or even result in a collapse.
Dampeners play an important role in the protection of structures, e.g., houses or similar building structures, and they exist in numerous variants. Dampeners may dampen the motion by means of a frictional force between two moving parts attached between structural members of the building or by means of a fluid being forced to flow between two chambers through a restricted tube. Such dampeners act to dampen the seismic, explosion, and wind loading shear, and not an axial cross brace manner. Some dampers are actively changing the dampening effect corresponding to external conditions, and other dampers are passive dampers having a constant dampening characteristic.
An example of a passive dampener is the use of a Buckling Restrained Brace (BRB) which incorporates one or more metallic core or center axial member passing through an exterior buckling-constraining concrete restraint. Such dampeners are heavy, costly to produce, and even more costly to assemble into a structural member of a building. In addition, the BRB dampener result in the metallic core experiencing plastic deformation and strain hardening resulting in permanent set and overall length change to due reacting the large compression and tension loads during a dampening event. The dampening event is a result of the horizontal movement that may occur, e.g., if the foundation of a building is displaced by an earthquake or by similar vibrations transmitted through the ground.
There is, therefore, a need in the art for an improved dampener that will handle these large compression and tension loads that are simpler to manufacture and are lighter weight due to the elimination of cast concrete, and have improved buckling response due to the integration of one or more cylinder of composite materials. Accordingly, the present disclosure provides for dissipating the energy of the seismic, explosion, or wind event by the plastic deformation of one or more circular rods of a metallic core, with the one or more composite cylinder providing the buckling restraint of the metallic rods.